SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a81a5a87a26d5539a8ec4d58a8f7d55e61d79d9f58994d5fb70ce974fb1e72d' 
  AND token = 'TYd/DHK7SY+4UJHicvKosDbLr2qvslkZh+/PEm3z5VU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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