Hi,
Please edit the file "administrator/components/com_hikashop/helpers/helper.php" and replace the line
$query = 'SELECT cart_id FROM '.hikashop_table('cart').' WHERE cart_modified < '.(time()-$period);
$database = JFactory::getDBO();
By
$database = JFactory::getDBO();
$query = 'SELECT cart_id FROM '.hikashop_table('cart').' WHERE cart_type = '.$database->Quote('cart').' AND cart_modified < '.(time()-$period);
It will fix your issue
(this patch will be include in the next HikaShop release).
Regards,