Back Squat
Warm up to a single at 80-90%
Then
10×3 @60%
E:1:30
Focus on loading on the way down and acceleration on the way up
Wake the system up with a heavy single and use that as a gauge for the effort you can put into a single rep. Now apply that to all thirty reps and make the intended improvements to your speed.
From the ground modification: Front Squats