My car-key broke off my key-ring.

The small loop at bottom right of photo is broken.

How can I fashion some method of securely attaching this to a key-ring?

Followup to ErinGoBragh's comment:

The key (or more accurately the transmitter housing) can't easily be taken apart, the battery is accessed by turning a screw to unlock a battery holder that slides out. I suspect the plastic is glued (or maybe solvent-welded) together.

After ErinGoBragh's comment and Tetsujin's answer I dug around a bit more assertively ...

Maybe there is some way to make a replacement for this small loop with its cruciform anchor-foot?

I'll probably go with Tetsujin's answer and find a donor for the part. I did briefly ponder bending a paperclip or using sugru/polymorph/epoxy + a screw-eye.