SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '308c48bf661df7a847712b18a1fb044e07012790ca328e0cb4de7b676c63becc' 
  AND token = 'jqXdlPvMmgZeXkxKNikwgoXDLdR72nv1mFgs8LQMYwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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