With the versatility of crossfit boxes, it is possible to perform a number of exercises using it within a circuit. It is best to alternate lower body and upper body exercises to provide some rest to the idle parts. Each can take about 30 seconds or so. Immediately move on to the next after completing an exercise.
This can be designed in many ways. You can begin with easy movements such as a lateral step on both sides before going into an inclined pushup. Then you might start with a box jump at a low height before moving on to a 360-degree plank. Do this in both directions if you can.
From time to time, you can move away from the box by doing plyo exercises that do not require it such as jumping jacks or jump rope. Then move on to an inclined side plank or a bridge.