If you mean a keyboard where a user interacting with your prototype could interactively type text into a text field inside your design, then no -- not yet. If you're interested in that, please upvote this item in our feature request list: Text input field with actions – Adobe XD UserVoice .
If you just want a static image of a keyboard to make your mockups more realistic looking, check out the "UI kit" files that come included with Adobe XD. You can access them from the welcome screen, or use File > Open UI Kit.
Hope that helps!