For four years I carried a Yubikey NEO (USB Type-A) in my pocket, on my keychain. And then it died (would no longer be recognized by any computer).
Crush-resistant and waterproof, YubiKey NEO is practically indestructible during normal use, weighs only 3g, and attaches to your keychain alongside your house and car keys
So, they didn’t explicitly say “carrying it on your keychain won’t kill it”, but they sure did imply it.
The wording for their new USB Type-A products is much more tepid:
Design & Durability: Water Resistant, Crush Resistant
Luckily, a few months after I bought the first one I bought a backup that I stored safely, so I wasn’t much put out. Here are the two keys side-by-side – click to see more detail than you need:
(After looking at that photo up close I realized that the problem could be that the two middle pins were touching. So I took a small screwdriver and carved them apart. And it works! But that doesn’t really undermine the point here, which is…)
So make sure you have a backup Yubikey 2FA hardware token, or you could be very unhappy when it gets damaged beyond use. Then you can carry your day-to-day key in your pocket without worry.