SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '472f6f29298444febd537ef1b2c5b40785654568d037c714c4a247ea38937848' 
  AND token = 'AQIsS6wmlD1keckMXFuvJWpqUgrbw8MlgA0VLsFsPcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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