SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    65082, 65503, 65087, 65501, 65500, 65502, 
    65938, 65884, 65836
  )

Query time 0.00048

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": 9,
      "filtered": 100,
      "attached_condition": "cscart_products.product_id in (65082,65503,65087,65501,65500,65502,65938,65884,65836)"
    }
  }
}

Result