SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '206681a00cfa423980269e60f84616ae2bc5bc2ad0db68d7c2d6efd1ffa0895d' 
  AND token = 'l5jMJs7lvW3+E3twbiLVIGBFZhj7KkXLnNqxB70zlkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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