SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b9eb27f5cbfb42e94ade3c7b57e8089a30a33c81111df7664e396afbba6545c' 
  AND token = 'AEJiOq9U7GAjy8bsgVVRHgSEe2mocwDcDDMHEXrj+Io=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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