Hi,
Right, you can edit the plugin directly and use this query
$query = 'SELECT * FROM '.hikashop_table('product').' WHERE '.
' product_quantity < '.(int)$this->stock_limit.' AND product_published = 1 AND product_quantity != -1 '.
' AND (product_sale_start = 0 OR product_sale_start < '.time().') AND (product_sale_end = 0 OR product_sale_end > '.time().')';
So only the published products and the products which are currently sold will be checked.
I will submit this patch and see with Nicolas if it's good for him. But I think that we will include it in the official plugin.
Regards,