SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    1621, 1907, 1955, 1663, 1674, 1490, 1746, 
    1831, 1832, 1591, 1737, 1805
  )

Query time 0.00087

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 (1621,1907,1955,1663,1674,1490,1746,1831,1832,1591,1737,1805)"
    }
  }
}