diff --git a/internal/api/oidc/introspect.go b/internal/api/oidc/introspect.go
index b98980358d9..26688e529be 100644
--- a/internal/api/oidc/introspect.go
+++ b/internal/api/oidc/introspect.go
@@ -14,97 +14,202 @@ import (
 )
 
 func (s *Server) Introspect(ctx context.Context, r *op.Request[op.IntrospectionRequest]) (_ *op.Response, err error) {
-	clientID, err := s.authenticateResourceClient(ctx, r.Data.ClientCredentials)
-	if err != nil {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	clientChan := make(chan *instrospectionClientResult)
+	go s.instrospectionClientAuth(ctx, r.Data.ClientCredentials, clientChan)
+
+	tokenChan := make(chan *introspectionTokenResult)
+	go s.introspectionToken(ctx, r.Data.Token, tokenChan)
+
+	var (
+		client *instrospectionClientResult
+		token  *introspectionTokenResult
+	)
+
+	// make sure both channels are always read,
+	// and cancel the context on first error
+	for i := 0; i < 2; i++ {
+		var resErr error
+
+		select {
+		case client = <-clientChan:
+			resErr = client.err
+		case token = <-tokenChan:
+			resErr = token.err
+		}
+
+		if resErr == nil {
+			continue
+		}
+		cancel()
+
+		// we only care for the first error that occured,
+		// as the next error is most probably a context error.
+		if err == nil {
+			err = resErr
+		}
+	}
+
+	// only client auth errors should be returned
+	var target *oidc.Error
+	if errors.As(err, &target) && target.ErrorType == oidc.UnauthorizedClient {
 		return nil, err
 	}
+
+	// all other errors should result in a response with active: false.
 	response := new(oidc.IntrospectionResponse)
-	tokenID, subject, err := s.getTokenIDAndSubject(ctx, r.Data.Token)
 	if err != nil {
 		// TODO: log error
 		return op.NewResponse(response), nil
 	}
-	if strings.HasPrefix(tokenID, command.IDPrefixV2) {
-		err = s.introspect(ctx, response, tokenID, subject, clientID)
+	if err = validateIntrospectionAudience(token.audience, client.clientID, client.projectID); err != nil {
+		// TODO: log error
 		return op.NewResponse(response), nil
 	}
-
-	err = s.storage.SetIntrospectionFromToken(ctx, response, tokenID, subject, clientID)
+	userInfo, err := s.storage.query.GetOIDCUserinfo(ctx, token.userID, token.scope, []string{client.projectID})
 	if err != nil {
+		// TODO: log error
 		return op.NewResponse(response), nil
 	}
+	response.SetUserInfo(userinfoToOIDC(userInfo, token.scope))
+	response.Scope = token.scope
+	response.ClientID = token.clientID
+	response.TokenType = oidc.BearerToken
+	response.Expiration = oidc.FromTime(token.tokenExpiration)
+	response.IssuedAt = oidc.FromTime(token.tokenCreation)
+	response.NotBefore = oidc.FromTime(token.tokenCreation)
+	response.Audience = token.audience
+	response.Issuer = op.IssuerFromContext(ctx)
+	response.JWTID = token.tokenID
 	response.Active = true
 	return op.NewResponse(response), nil
 }
 
-func (s *Server) authenticateResourceClient(ctx context.Context, cc *op.ClientCredentials) (clientID string, err error) {
+type instrospectionClientResult struct {
+	clientID  string
+	projectID string
+	err       error
+}
+
+func (s *Server) instrospectionClientAuth(ctx context.Context, cc *op.ClientCredentials, rc chan<- *instrospectionClientResult) {
+	clientID := cc.ClientID
+
 	if cc.ClientAssertion != "" {
 		verifier := op.NewJWTProfileVerifier(s.storage, op.IssuerFromContext(ctx), 1*time.Hour, time.Second)
 		profile, err := op.VerifyJWTAssertion(ctx, cc.ClientAssertion, verifier)
 		if err != nil {
-			return "", err
+			rc <- &instrospectionClientResult{
+				err: oidc.ErrUnauthorizedClient().WithParent(err),
+			}
+			return
 		}
-		return profile.Issuer, nil
-	}
-
-	if err = s.storage.AuthorizeClientIDSecret(ctx, cc.ClientID, cc.ClientSecret); err != nil {
-		if err != nil {
-			return "", err
+		clientID = profile.Issuer
+	} else {
+		if err := s.storage.AuthorizeClientIDSecret(ctx, cc.ClientID, cc.ClientSecret); err != nil {
+			if err != nil {
+				rc <- &instrospectionClientResult{
+					err: oidc.ErrUnauthorizedClient().WithParent(err),
+				}
+				return
+			}
 		}
-	}
-	return cc.ClientID, nil
-}
 
-func (s *Server) getTokenIDAndSubject(ctx context.Context, accessToken string) (idToken, subject string, err error) {
-	provider := s.Provider()
-	tokenIDSubject, err := provider.Crypto().Decrypt(accessToken)
-	if err == nil {
-		splitToken := strings.Split(tokenIDSubject, ":")
-		if len(splitToken) != 2 {
-			return "", "", errors.New("invalid token format")
-		}
-		return splitToken[0], splitToken[1], nil
 	}
 
-	verifier := op.NewAccessTokenVerifier(op.IssuerFromContext(ctx), s.storage.keySet)
-	accessTokenClaims, err := op.VerifyAccessToken[*oidc.AccessTokenClaims](ctx, accessToken, verifier)
-	if err != nil {
-		return "", "", err
-	}
-	return accessTokenClaims.JWTID, accessTokenClaims.Subject, nil
-}
-
-func (s *Server) introspect(ctx context.Context, introspection *oidc.IntrospectionResponse, tokenID, subject, clientID string) (err error) {
 	// TODO: give clients their own aggregate, so we can skip this query
 	projectID, err := s.storage.query.ProjectIDFromClientID(ctx, clientID, false)
 	if err != nil {
-		return errz.ThrowPermissionDenied(nil, "OIDC-Adfg5", "client not found")
+		rc <- &instrospectionClientResult{err: err}
+		return
 	}
 
-	token, err := s.storage.query.ActiveAccessTokenByToken(ctx, tokenID)
-	if err != nil {
-		return err
+	rc <- &instrospectionClientResult{
+		clientID:  clientID,
+		projectID: projectID,
 	}
-	if !slices.ContainsFunc(token.Audience, func(aud string) bool {
-		return aud == token.ClientID || aud == projectID
-	}) {
-		return errz.ThrowPermissionDenied(nil, "OIDC-sdg3G", "token is not valid for this client")
-	}
-
-	userInfo, err := s.storage.query.GetOIDCUserinfo(ctx, token.UserID, token.Scope, []string{projectID})
-	if err != nil {
-		return err
-	}
-	introspection.SetUserInfo(userinfoToOIDC(userInfo, token.Scope))
-	introspection.Scope = token.Scope
-	introspection.ClientID = token.ClientID
-	introspection.TokenType = oidc.BearerToken
-	introspection.Expiration = oidc.FromTime(token.AccessTokenExpiration)
-	introspection.IssuedAt = oidc.FromTime(token.AccessTokenCreation)
-	introspection.NotBefore = oidc.FromTime(token.AccessTokenCreation)
-	introspection.Audience = token.Audience
-	introspection.Issuer = op.IssuerFromContext(ctx)
-	introspection.JWTID = tokenID
-
-	return nil
+}
+
+type introspectionTokenResult struct {
+	tokenID         string
+	userID          string
+	subject         string
+	clientID        string
+	audience        []string
+	scope           []string
+	tokenCreation   time.Time
+	tokenExpiration time.Time
+	isPAT           bool
+
+	err error
+}
+
+func (s *Server) introspectionToken(ctx context.Context, accessToken string, rc chan<- *introspectionTokenResult) {
+	var tokenID, subject string
+
+	if tokenIDSubject, err := s.Provider().Crypto().Decrypt(accessToken); err == nil {
+		split := strings.Split(tokenIDSubject, ":")
+		if len(split) != 2 {
+			rc <- &introspectionTokenResult{err: errors.New("invalid token format")}
+			return
+		}
+		tokenID, subject = split[0], split[1]
+	} else {
+		verifier := op.NewAccessTokenVerifier(op.IssuerFromContext(ctx), s.storage.keySet)
+		claims, err := op.VerifyAccessToken[*oidc.AccessTokenClaims](ctx, accessToken, verifier)
+		if err != nil {
+			rc <- &introspectionTokenResult{err: err}
+			return
+		}
+		tokenID, subject = claims.JWTID, claims.Subject
+	}
+
+	if strings.HasPrefix(tokenID, command.IDPrefixV2) {
+		token, err := s.storage.query.ActiveAccessTokenByToken(ctx, tokenID)
+		if err != nil {
+			rc <- &introspectionTokenResult{err: err}
+			return
+		}
+		rc <- &introspectionTokenResult{
+			tokenID:         tokenID,
+			userID:          token.UserID,
+			subject:         subject,
+			clientID:        token.ClientID,
+			audience:        token.Audience,
+			scope:           token.Scope,
+			tokenCreation:   token.AccessTokenCreation,
+			tokenExpiration: token.AccessTokenExpiration,
+		}
+		return
+	}
+
+	token, err := s.storage.repo.TokenByIDs(ctx, subject, tokenID)
+	if err != nil {
+		rc <- &introspectionTokenResult{
+			err: errz.ThrowPermissionDenied(err, "OIDC-Dsfb2", "token is not valid or has expired"),
+		}
+		return
+	}
+	rc <- &introspectionTokenResult{
+		tokenID:         tokenID,
+		userID:          token.UserID,
+		subject:         subject,
+		clientID:        token.ApplicationID, // check correctness?
+		audience:        token.Audience,
+		scope:           token.Scopes,
+		tokenCreation:   token.CreationDate,
+		tokenExpiration: token.Expiration,
+		isPAT:           token.IsPAT,
+	}
+}
+
+func validateIntrospectionAudience(audience []string, clientID, projectID string) error {
+	if slices.ContainsFunc(audience, func(entry string) bool {
+		return entry == clientID || entry == projectID
+	}) {
+		return nil
+	}
+
+	return errz.ThrowPermissionDenied(nil, "OIDC-sdg3G", "token is not valid for this client")
 }