If you think you have a good reason for it to be unlocked, you can post about it on meta board for moderator to unlock it for you. Some users had tried this before and moderator unlock it.
If I were the OP, then I'd rather PM one of the moderators to unlock the thread and tell them why it's unlock it with good reason. That's much more correct in my opinion compared to creating a request thread to unlock a thread that has been locked by a moderator.
Wouldn’t it be good if we had the stats who locked the thread? I can't see it anywhere for now.
I don't think every moderator's actions should be accompanied by evidence like when they edit and merge multiple posts in a row or move a thread to another board. You can't expect proof of who locked thread if it wasn't yours or if the OP didn't tell you about his actions.