Try this query i wrote for you, just change the GetDate() to be how many days old it must be
USE EnterpriseVaultDirectory
SELECT A.ArchiveName AS "Archive Name",
EME.LastModified AS "Last Synchronized",
IV.YoungestArchivedDateUTC AS "Last Item Archived On",
IV.OldestArchivedDateUTC AS "First Item Archived On",
IV.OldestItemDateUTC AS "Oldest Items Sent Date",
IV.YoungestItemDateUTC AS "Youngest Items Sent Date"
FROM Archive A, Root R, ExchangeMailboxEntry EME, IndexVolume IV
WHERE IV.RootIdentity = R.RootIdentity
AND R.RootIdentity = A.RootIdentity
AND R.VaultEntryID = EME.DefaultVaultID
AND IV.YoungestArchivedDateUTC < GetDate()-30
ORDER BY IV.YoungestArchivedDateUTC DESC
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