SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    1421, 1406, 1422, 1413, 753, 566, 1021, 
    536, 686, 519, 764, 1226
  )

Query time 0.00062

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": 12,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (1421,1406,1422,1413,753,566,1021,536,686,519,764,1226)"
    }
  }
}