There are three types of speed up tokens available. They can be received as rewards for completing missions and events, or purchased through the Market. They can also be obtained by clicking the Speed Up button in the building menu or below your fleet on the main screen.
Construction Speed-Up tokens reduce the structure construction time by 5 minutes, 30 minutes, or 1 hour.
Home Speed-Up tokens reduce the fleet return speed by 5 minutes, 30 minutes, or 1 hour.
Universal Speed-Up tokens reduce the time needed to return to home base or construct structures by 5 minutes, 15 minutes, 3 hours, or 8 hours. Once a structure is being built or upgraded, or when your fleet is returning to base, you will have the option to use these speed-up tokens.