SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1517811a95d1e0d58e075d1fd6281ee4bbbf45b8d554405cd401ccbc68c2b9c0' 
  AND token = '/aYcpb8VKhZ+EEk835iWDzWYJnXs30kWz5+SA9IgzNM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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