SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5176d4dc90b893a70534b330563891f2ce6588000be989214f9b87dc75dbf290' 
  AND token = 'LJirBBYGpIuKpfHQTI2qwVZhGVgEBjkTbrH/D12oN3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}