Stardew valley and Keep Talking and Nobody Explodes humble links for it
or $12 Paypal fees on you if any
if you're lucky, someone might do a 1:1 trade for Borderlands the Presequel for your Stardew. Good luck, though.
also, for $12.. I would just wait for the Summer Sale unless you need it before then. It'll be like $10.. maybe?
I think you're out of luck and most people don't want raw keys unless you're trading with someone that is going to activate it or can trust you. Just wanting it tonight soon is probably why you won't find someone unless you start looking actively using the search.
Here's a tiny bit of help and you might get lucky if you can do a 1:1 trade with that user, but I don't think anyone is going to respond back to you that fast before 'tonight'
https://www.steamtrades.com/trade/IxprZ/h-borderlands-the-pre-sequel-sekai-bundle-w-wishlist
https://www.steamtrades.com/trades/search?have=stardew%20valley&want=Borderlands%3A%20The%20Pre-Sequel
https://www.steamtrades.com/trades/search?have=stardew%20valley&want=Keep%20Talking%20and%20Nobody%20Explodes
edit: just browse the threads. I would stick to 1:1 and realize most people with over 50..? feedback will likely not want raw keys, so mention it when you post. Just try to trade with someone who may want to play the game, I guess, so it makes it easier to trade.
Stardew Valley
Stanley Parable
Keep Talking and Nobody Explodes
Borderlands the Presequel
I would also take Borderlands for paypal for around $12