SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    12987, 12988, 12989, 12990, 12991, 12992, 
    12993, 12994, 10403, 10404, 10405, 
    15781, 10406, 10407, 10408, 10409, 
    10410, 10411, 10412, 12853
  )

Query time 0.00051

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": 20,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (12987,12988,12989,12990,12991,12992,12993,12994,10403,10404,10405,15781,10406,10407,10408,10409,10410,10411,10412,12853)"
    }
  }
}