There was JamBTC, not an official exchange, but you could sell coins there. But the owner recently exit-scammed everyone.
Just a reminder, if you sell your coins on shit exchanges, do so in small batches, and withdraw immediately.

There is no current exchange that I know of. You can offer to sell your coins HERE and someone will buy them. Last price on JamBTC was around 200 sats.  Or just HODL, that's what I'm doing.  Some exchange will pick them up, probably soon.  Maybe apply to TradeOgre?  LOL. Another exchange that will probably eventually exit scam everyone, but at least for now it works, and works well, with actual customer service (contact them on Twitter).

I'm sure the KOTO team is working on getting listed on a legitimate high-quality exchange.