Count 1000 rows with this query?

I got this query, where i need to see how many matches there is, in that way I can see how many notifications is NOT seen. But - Let's say i where to count 1000 rows, is this a bad query?

$notifications = Self::query()
    ->columns(array('COUNT(Models\UsersNotifications.id) AS count', 'COUNT(seen.id) AS cnt'))
    ->leftJoin('Models\UsersNotificationsSeen', 'Models\UsersNotifications.id = seen.notificationid', 'seen')
    ->where('Models\UsersNotifications.userid = :userid:', array('userid' => $userid))
    ->limit(1)
    ->execute();