fix(premium-podcasts): update query to validate subscription

modules/PremiumPodcasts/Models/SubscriptionModel.php

@@ -118,9 +118,11 @@ class SubscriptionModel extends Model
             ->where([
                 'token'  => hash('sha256', $token),
                 'status' => 'active',
-                'expires_at' => null,
             ])
+            ->groupStart()
+            ->where('expires_at', null)
             ->orWhere('`expires_at` > UTC_TIMESTAMP()', null, false)
+            ->groupEnd()
             ->first();
     }