SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    9942, 9943, 9944, 10744, 10745, 10746, 
    9789, 10547, 10650, 10726, 10649, 10648, 
    10647, 10645, 10646, 10653, 9873, 10604, 
    10605, 10654
  )

Query time 0.00046

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 (9942,9943,9944,10744,10745,10746,9789,10547,10650,10726,10649,10648,10647,10645,10646,10653,9873,10604,10605,10654)"
    }
  }
}