SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4281ddf8fbc9508793cdceaa07f56186dfc2e8c3d48bf6934f7dcba42d7efe26' 
  AND token = 'UDB7GueHjkAgWCsh35Bqy5456IR+bCa8ORumhKTj3HE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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