SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    12603, 12608, 12606, 12604, 12602, 12600, 
    15956, 15957, 15958, 10692, 10693, 
    10695, 10696, 10698, 10699, 10701, 
    10724, 10725, 10668, 10669
  )

Query time 0.00072

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 (12603,12608,12606,12604,12602,12600,15956,15957,15958,10692,10693,10695,10696,10698,10699,10701,10724,10725,10668,10669)"
    }
  }
}