How to compare xmin and txid_current() after transactions ID wraparound?
You can strip the added epoch to match the value in xmin, i.e. extract the 4-byte integer from the bigint. Since xmin is type xid and not (signed!) integer, we compare the text representation instead:

SELECT * FROM test
WHERE  xmin::text = (txid_current() % (2^32)::bigint)::text;


Detailed explanation:


How to view tuples changed in a PostgreSQL transaction?