How interesting. I never knew that the seedpods were called keys.
I did a little googling and it appears that both maple and ash keys are non toxic and edible.
I agree with lleighmay I have lots of maple around here and my chickens won't eat them. Maybe if they were shelled, but that seems like way too much work to me.
The Ash trees around here don't have keys. They produce clusters of red berries.
I've never seen the birds here eat them. The neighbor's 2 year old did. That tree was cut down the next day. He was and is OK. When I was a kid the birds did eat the berries on the mountain ash.
Imp- You'll have to let us know if your chickens will eat them.