I have only once before seen a key with a hole drilled in the end of it and that was to hang a bunch of keys up, where there were so many keys on a keyring, that there was no room between them to hang the bunch up by the actual keyring - So one cylinder key had a hole drilled in the end, so the whole bunch could be hung up from just one key. I wonder if at any time this had been part of such a bunch?
Overall, it looks to be just about 2" long, give or take a millimeter. I have seen keys like that (sans hole in the end). Look at the keyway, there are no "ridges" in the sides of the key to make it harder to get picks in the lock, just thinning of the key's edge to make cutting it quicker and cheaper. The actual "skyline" of the cuts is very basic, the lock would be a doddle to pick and this is what reminded me - I've seen them on toys and especially on inexpensive display cases, like boxes for floppy disks, CDs, etc. The key for my own computer CD boxes looks almost identical, except for it being smaller.
The shoulder has been crudely cut away, I have only seen this done for where someone has fitted a lock too close to existing door "furniture". That could be a handle, but would seem more likely to have been the escutcheon of the old lock it was replacing or something similar to that.
So my guess is it was the key for a cabinet, where the old lock became unusuable for some reason and a cheap cabinet lock was fitted bt the owner, who either mistakenly fitted it too close to the old lock, or had no choice but to fit it there as it was the only place where the lock could be secured to the door(s).
With it being brass, not nickle-plated, my guess is that the key (and so the lock it came from) was American, not Chinese made.
I also guess it had either been at some time been on a keyring with lots of other keys, or if the owner knew a little bit about keys, then the hole in the end might have been drilled to identify that key specifically from the others (as it would not affect the functioning of the key).
Getting a magnifying glass on the picture seems to confim my guesses, except for the teeth of the key looking "stepped" when you look very closely. That is either that it was cut very crudely (someone was trying to cut their own key from another key?), or possibly it is significant wear. This might be, since the web of the key looks quite thin and the brass is poor quality and poorly-cast. Just look at the defect on the head of the key (discolouration). That could be the brass was too hot, or too cold when cast. There's even a slight possibility of a tiny bit of "dampness" in the mould, causing the brass to cool too quickly there, or just possibly the mould itself was damaged there. I cannot really tell from the picture I'm afraid.