Expiry warnings: Pre-fetch expiry column

src/pretix/base/services/orders.py

@@ -875,12 +875,13 @@ def expire_orders(sender, **kwargs):
 def send_expiry_warnings(sender, **kwargs):
     today = now().replace(hour=0, minute=0, second=0)
     days = None
+    settings = None
     event_id = None
 
     for o in Order.objects.filter(
         expires__gte=today, expiry_reminder_sent=False, status=Order.STATUS_PENDING,
         datetime__lte=now() - timedelta(hours=2), require_approval=False
-    ).only('pk', 'event_id').order_by('event_id'):
+    ).only('pk', 'event_id', 'expires').order_by('event_id'):
         if event_id != o.event_id:
             settings = o.event.settings
             days = cache.get_or_set('{}:{}:setting_mail_days_order_expire_warning'.format('event', o.event_id),