SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    3983, 3984, 3981, 3985, 3982, 4208, 4213, 
    4210, 4211, 4209, 4212
  )

Query time 0.00030

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": 11,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (3983,3984,3981,3985,3982,4208,4213,4210,4211,4209,4212)"
    }
  }
}