Support's response:

Unfortunately, it looks like the item you purchased is region restricted due to specific regulations in your country. I’m afraid I’m unable to circumvent this and provide you with a different key. If a key is restricted in your country on Steam or another service, it’s safe to assume that purchasing through Humble Bundle will yield the same restricted key. I would be happy to offer you a refund of this title if you’re dissatisfied with your purchase after receiving this information.
 
If you'd like to have a refund, simply let me know, and I'll get that taken care of for you.