How Can I Find Dungeon Keys More Efficiently?

So I randomly find key holders throughout the map but I don't know an efficient way to farm them in excess or where I should go to do so. If anyone can point me in the right direction or let me know where the spawns or it would be greatly appreciated :D

 

The problem with key guardians is even if you farm in the right area, you still have to rely on RNG in order for them to actually spawn. However, here's just some spots where they spawn pretty commonly for me.

Decrepit Sewers: Pretty much anywhere from Ragni through the Nivla Forest.
Infested Pit: The Black Road, some areas of the Time Valley, and the outskirts of the Nivla Forest.
Lost Sanctuary: Around the Roots of Corruption and sometimes the Time Valley.
Underworld Crypt: Near/In Ancient Nemract.
Sandswept Tomb: Basically anywhere in the desert or mesa.
Ice Barrows: Around the entrance of Llevigar/the Nesaak forest. Occasionally spawns in the Ice Nations as well, but not as reliable.
Undergrowth: Troms and Dernel Jungle along with the Olux swamp.
Galleon's: Dernel Jungle and the Dark Forest.
Corrupted Decrepit: The outskirts of the Dark Forest and in the Kander Forest.
Corrupted Infested: The Light Forest.
Corrupted Lost Sanctuary: Around Lake Gylia and the entrance of CotL (Canyon of the Lost).
Corrupted Underworld: Around CotL.
Corrupted Sandswept Tomb: Around CotL and Corkus.
Corrupted Ice Barrows: Around Corkus and probably MH (Molten Heights).
Fallen Factory: Around Corkus and MH.

 

Which ones in particular? If you need a bunch quickly, you're usually better off buying them.

 

sanctuary, underworld and sst

 

Lost Sanctuary - just run around the Little Wood, they're common over there and usually not anywhere else. Underworld Crypt - Ancient Nemract. SST - near the WynnExcavation site is usually the best place.

 

Near the factory in Corkus the ice barrows guardian spawn rate is crazy!

I was grinding robots for a mini quest but those things kept popping up left right and center :/ (5 of them!!)