Apply suggestion from @john-westcott-iv

Author: john-westcott-iv

ansible_base/oauth2_provider/models/access_token.py

@@ -82,6 +82,9 @@ def is_valid(self, scopes=None):
             self.last_used = now()
 
             def _update_last_used():
+                # QuerySet.update() is used instead of save() to avoid a race condition
+                # where concurrent requests updating last_used can cause DatabaseError.
+                # This is safe because last_used is a trivial field with no save() side effects.
                 OAuth2AccessToken.objects.filter(pk=self.pk).update(last_used=self.last_used)
 
             connection.on_commit(_update_last_used)