SELECT 
  p.product_id, 
  ifnull(
    count(dp.post_id), 
    0
  ) as discussion_amount_posts 
FROM 
  cscart_discussion 
  INNER JOIN cscart_products as p ON (
    cscart_discussion.object_id = p.product_id
  ) 
  INNER JOIN cscart_discussion_posts as dp ON (
    cscart_discussion.thread_id = dp.thread_id 
    AND cscart_discussion.object_type = 'P' 
    AND cscart_discussion.company_id = 1
  ) 
WHERE 
  dp.status = 'A' 
  and p.product_id in (
    130, 51106, 51107, 51112, 51111, 51110, 
    51109, 51108, 128, 51118, 51117, 51116, 
    51115, 51114, 51113, 51165, 51164, 
    51163, 51162, 51161, 52, 51183, 20, 
    51188, 51187, 51186, 51185, 51184, 
    51232, 12, 51238, 51237, 51236, 51235, 
    51234, 51233, 51243, 51242, 51241, 
    51240, 51239, 36, 51246, 51245, 51244, 
    35, 51248, 51247, 51253, 51252, 51251, 
    51250, 51249, 34, 51256, 51255, 51254, 
    33, 32, 51265, 51264, 51263, 51262, 
    51261, 51260, 51259, 110, 51273, 147, 
    51277, 51276, 51275, 51274, 51281, 
    51280, 51279, 51278, 51282, 7, 16, 114, 
    89, 51390, 51391, 51392, 51393, 51394
  ) 
GROUP BY 
  p.product_id

Query time 0.00062

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}