I'm trying to make a desktop setup powered by my laptop (yoga 730) but I don't have an available USB port to plug in a Corsair K55. should I get a USB hub (even though I only need one USB), or is there an alternate route?
Yes, in general USB keyboards will work through a USB hub. The only caveat is making sure there is enough power for each device connected, so hubs with their own power source (e.g. DC power supply) can handle more devices than passive ones (which will be restricted by how much power the USB port on the computer can supply). Personally, I have a passive 2 port hub that I have a mouse and keyboard plugged into and both devices work fine.
EDIT: in response to the comment left by @Ale..chenski, according to the research I did into the Lenovo Yoga 730, it has 1 x USB 3.0 and 2 x USB Type C. (source) You could plug the keyboard directly into the USB 3.0 port, (or plug in a USB hub into it if you want to add other devices, including the keyboard). You can also get a USB type C to A adapter to plug in the keyboard (and hub) like this one from Amazon.