SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    10704, 10705, 10706, 10707, 10708, 10709, 
    10710, 10711, 10712, 10301, 10302, 
    10303, 10304, 9945, 10601, 9727, 9728, 
    9729, 9730, 9731
  )

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 (10704,10705,10706,10707,10708,10709,10710,10711,10712,10301,10302,10303,10304,9945,10601,9727,9728,9729,9730,9731)"
    }
  }
}