Before the introduction of struck coinage in Celtic lands, solid bronze ring money was used as a currency in the Danube area, France then later in England and Ireland from 800 BC to 50 BC.
It's possible, but it looks in unbelievably good nick for something around 2,000 years old... and I would want a bit more information about how you came by it before venturing any further opinion. They come in all manner of variants but I haven't seen one like yours before, and there are sellers passing off all kinds of other ring-shaped items as Celtic ring money.
Primitive currency items is one of my collecting areas. Here's a couple of Celtic ring money pieces from my collection (personal finds):