I hunted War Golems for a long time and never obtained a Tin Key. To get it in 2 hours would probably be a miracle, but possible. If I had to choose over Frost Dragons or War Golems I would probably pick War Golems. The chances of profiting at Frost Dragons can be very slim and the experience is tough.
Here's a tutorial of the spawn I recommend and a pally level 140 enjoying it:
https://www.youtube.com/watch?v=AMTiThzf6Jk
He's getting EXP: 480k/hr with 150% PROFIT 140k+/hr (so I would pick War Golems for the fun of the XP and the profit!)
Factory Quarter (40+ here (4 Gear Wheels required per entry. Four machines line the platform to the right or left. Use one of the machines with the gearwheels present in your backpack. You will receive the message, "You insert all 4 gear wheels, thus adjusting the teleporter to transport you to the left side.")
Here's how you get to the spawn I recommend go here in Yalahar and keep going down until your at the last floor and go south and then just walk in to the spawn left or right :)
https://tibia.fandom.com/wiki/War_Golem#Location