SQL Explain

{{{Executed SQL}}{{Executed SQL}}{{Executed SQL}}{{Mage_Core}}}
SELECT max(qo) AS des_qty,`product_id`,`parent_item_id` FROM ( SELECT sum(`qty_ordered`) AS qo,`product_id`,created_at,store_id,`parent_item_id` FROM sales_flat_order_item GROUP BY `product_id` ) AS t1 where store_id AND parent_item_id is null AND created_at between '2019-08-9' AND '2020-08-08 18:50:58' GROUP BY `product_id` ORDER BY des_qty DESC LIMIT 6
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL 39 Using where; Using temporary; Using filesort
2 DERIVED sales_flat_order_item ALL 39 Using temporary; Using filesort