SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6eec921cf18e518ad3fda6726b97c4bb92fa85dd2451e39edbd5a045f394a728' 
  AND token = 'H7za3YZLrgAZBDXwTtHXPuxeUrYLkf3PKGQUNNvov9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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