Key Compendium
Unrest Keys
Tarnished Bronze Key - drops from 'a priest of najena', unlocks nothing. (You need it for The Mystic Cloak quest in Najena.
Small Stone Key - drops from 'a reanimated hand', unlocks the magus room.
Polished Brass Key - drops from 'reclusive ghoul magus', unlocks the bar room.
Scuffed Silver Key - drops from 'an undead barkeep', unlocks the tower.
Cracked Glass Key - drops from 'an undead knight of Unrest', unlocks the basement
Note: These keys only drop in classic era and are only needed during classic era, afterwards they become unlocked.
Befallen Keys
Splintered Wooden Key - drops from a shadowknight (Dark Elf Male), in the room to the right of the well room.
Smoked Glass Key - drops from a shadowknight (Troll) in the cave system behind the fake wall, or dropping down the well. Unlocks the Dark Elf area that includes Baron Telyx V`Zher.
Note: If you're sufficiently high level and heading to Befallen to farm an item, you don't need to keep the keys permanently. When you enter the zone, run to Asaka L`Rei's room, hop down the well and find the troll shadowknight in the cave system. They drop all three keys.