SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    12656, 12645, 12651, 12597, 12615, 12603, 
    12629, 12604, 9776, 9777, 9781, 9775, 
    9778, 9779, 9780, 9782, 9790, 9787, 
    9791, 9792
  )

Query time 0.00070

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 20,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (12656,12645,12651,12597,12615,12603,12629,12604,9776,9777,9781,9775,9778,9779,9780,9782,9790,9787,9791,9792)"
    }
  }
}