SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    312881, 312873, 312841, 312842, 312847, 
    312848, 312840, 312846, 312838, 312839, 
    312854, 312876
  )

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.0216566,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_products",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "loops": 1,
          "rows": 12,
          "cost": 0.0216566,
          "filtered": 100,
          "attached_condition": "cscart_products.product_id in (312881,312873,312841,312842,312847,312848,312840,312846,312838,312839,312854,312876)"
        }
      }
    ]
  }
}