Any suggestions or clues how I might optimize this SQL, it is running via ADO?

lcPreviousId = ThisRecord.Id

* Previous record:
SELECT * FROM Master WHERE (Id < lcPreviousId) UNION ;
SELECT * FROM Archive WHERE (Id < lcPreviousId) ;
ORDER BY Id DESC

* Next record:
SELECT * FROM Master WHERE (Id > lcPreviousId) UNION ;
SELECT * FROM Archive WHERE (Id > lcPreviousId) ;
ORDER BY Id ASC

Thsnks,
Nick