The Overseer's Office Key is one of the many keys that you will find in The Cycle Frontier. It's labeled "Nutrition Farms," according to the description, but it doesn't say where you can use it.
Where to use the Overseer's Office Keycard – The Cycle Frontier
There are several keys you will come across while exploring the Crescent Falls map in The Cycle Frontier. Most of the time, though, these keys won't tell you where you can use them.
They give little hints here and there, but if you're struggling to figure them out, then this guide is for you.
The most important tip you can find is in the description of the key itself. As mentioned, it is labeled "Nutrition Farms". That means the specific place you can use it is the Nutrition Farms Processing area. You can find this area in the southwest part of the map, just above the Favela.