Don't wait for a flood. Clean your drain immediately if you notice:
If the filter is clean but the water won't budge, the "kink or clog" is likely in the hose. how to clean a dishwasher drain
Rinse it under hot water. Use a soft brush and dish soap to remove greasy residue. Don't wait for a flood
Twist and lift the filter out. If you aren't sure how yours comes out, check your manual or look for instructions from manufacturers like Whirlpool or Bosch. how to clean a dishwasher drain
If you have a small cylinder on your sink (an air gap), unscrew the cap and check for food buildup inside. You can often clear this with a bottle brush.