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 (
    180, 181, 182, 183, 184, 185, 186, 187, 
    188, 189, 190, 191, 1, 5, 7, 8, 9, 10, 11, 
    12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 
    22, 23, 24
  ) 
GROUP BY 
  p.product_id

Query time 0.00112

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "p.product_id",
      "temporary_table": {
        "nested_loop": [
          {
            "table": {
              "table_name": "dp",
              "access_type": "ALL",
              "possible_keys": ["thread_id", "thread_id_2"],
              "rows": 17,
              "filtered": 100,
              "attached_condition": "dp.`status` = 'A'"
            }
          },
          {
            "table": {
              "table_name": "cscart_discussion",
              "access_type": "eq_ref",
              "possible_keys": ["PRIMARY", "object_id", "idx_company_id"],
              "key": "PRIMARY",
              "key_length": "3",
              "used_key_parts": ["thread_id"],
              "ref": ["n764025_kutubminar123.dp.thread_id"],
              "rows": 1,
              "filtered": 100,
              "attached_condition": "cscart_discussion.company_id = 1 and cscart_discussion.object_type = 'P'"
            }
          },
          {
            "table": {
              "table_name": "p",
              "access_type": "eq_ref",
              "possible_keys": ["PRIMARY"],
              "key": "PRIMARY",
              "key_length": "3",
              "used_key_parts": ["product_id"],
              "ref": ["n764025_kutubminar123.cscart_discussion.object_id"],
              "rows": 1,
              "filtered": 100,
              "attached_condition": "p.product_id in (180,181,182,183,184,185,186,187,188,189,190,191,1,5,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24)",
              "using_index": true
            }
          }
        ]
      }
    }
  }
}