If I play wages of pain to kill a ravensbloom prefect, can I use the prefect ability to kill the gold gear token ?

No — the Prefect is dead before its trigger can be paid for. Wages of Pain deals 3 to the 3‑Might Prefect, and the Gold token is played as its second instruction, so "when an opponent plays a gear" does fire — but Wages of Pain finishes resolving before any trigger is addressed (Rule 158.3), and the cleanup right after kills the Prefect for lethal damage (Rule 323.5).

Cleanups are Outstanding Tasks, and HOT FEPR handles Tasks before pending chain items (Rule 334), so the Prefect is in the trash by the time its ability would finalize. "Banish me" is the base cost of that triggered ability (Rules 383.3.b, 204.3.a) and must be paid to finalize it (383.3.b.1); once the Prefect is off the board there's nothing on board to banish as "me," so the ability never goes on the chain and the Gold token survives. Note there's no earlier window either — before Wages of Pain resolves, no gear has been played, and the Prefect's ability is a trigger, not a Reaction.

If the Prefect had lived through the 3 damage (Might boost, prevention, etc.), then yes — its controller could banish the Prefect to banish your Gold token. And that's a banish, not a kill, so nothing that cares about gear being killed would see it.