diff --git a/axes/admin.py b/axes/admin.py
index 92a03ca..877ab75 100644
--- a/axes/admin.py
+++ b/axes/admin.py
@@ -56,9 +56,7 @@ class AccessAttemptAdmin(admin.ModelAdmin):
         return False
 
     def expiration(self, obj: AccessAttempt):
-        if hasattr(obj, "expiration") and obj.expiration.expires_at:
-            return obj.expiration.expires_at
-        return _("Not set")
+        return obj.expiration.expires_at if hasattr(obj, "expiration") else _("Not set")
 
 class AccessLogAdmin(admin.ModelAdmin):
     list_display = (
diff --git a/axes/handlers/database.py b/axes/handlers/database.py
index cd2ca77..6f53a5a 100644
--- a/axes/handlers/database.py
+++ b/axes/handlers/database.py
@@ -400,7 +400,7 @@ class AxesDatabaseHandler(AbstractAxesHandler, AxesBaseHandler):
 
         if settings.AXES_USE_ATTEMPT_EXPIRATION:
             threshold = timezone.now()
-            count, _ = AccessAttempt.objects.filter(expiration__expires_at__lt=threshold).delete()
+            count, _ = AccessAttempt.objects.filter(expiration__expires_at__lte=threshold).delete()
             log.info(
                 "AXES: Cleaned up %s expired access attempts from database that expiry were older than %s",
                 count,
@@ -408,7 +408,7 @@ class AxesDatabaseHandler(AbstractAxesHandler, AxesBaseHandler):
             )
         else:
             threshold = get_cool_off_threshold(request)
-            count, _ = AccessAttempt.objects.filter(attempt_time__lt=threshold).delete()
+            count, _ = AccessAttempt.objects.filter(attempt_time__lte=threshold).delete()
             log.info(
                 "AXES: Cleaned up %s expired access attempts from database that were older than %s",
                 count,
diff --git a/axes/migrations/0010_accessattemptexpiration.py b/axes/migrations/0010_accessattemptexpiration.py
index ef7e5a6..74b3689 100644
--- a/axes/migrations/0010_accessattemptexpiration.py
+++ b/axes/migrations/0010_accessattemptexpiration.py
@@ -1,4 +1,4 @@
-# Generated by Django 5.2.1 on 2025-06-08 12:44
+# Generated by Django 5.2.1 on 2025-06-10 20:21
 
 import django.db.models.deletion
 from django.db import migrations, models
@@ -28,9 +28,7 @@ class Migration(migrations.Migration):
                 (
                     "expires_at",
                     models.DateTimeField(
-                        blank=True,
                         help_text="The time when access attempt expires and is no longer valid.",
-                        null=True,
                         verbose_name="Expires At",
                     ),
                 ),
diff --git a/axes/models.py b/axes/models.py
index 3c51c6e..5658cab 100644
--- a/axes/models.py
+++ b/axes/models.py
@@ -61,8 +61,6 @@ class AccessAttemptExpiration(models.Model):
     )
     expires_at = models.DateTimeField(
         _("Expires At"),
-        null=True,
-        blank=True,
         help_text=_("The time when access attempt expires and is no longer valid."),
     )