SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    312456, 312443, 312448, 312451, 312444, 
    312455, 312449, 312460, 461271, 461010, 
    461009, 312446
  )

Query time 0.00041

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 (312456,312443,312448,312451,312444,312455,312449,312460,461271,461010,461009,312446)"
        }
      }
    ]
  }
}