SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    347, 344, 335, 334, 333, 332, 331, 330, 
    306, 300, 298, 297, 296, 295, 294, 293, 
    292, 291
  )

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_products",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "rows": 18,
          "filtered": 100,
          "index_condition": "cscart_products.product_id in (347,344,335,334,333,332,331,330,306,300,298,297,296,295,294,293,292,291)"
        }
      }
    ]
  }
}