PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 12
Situational Awareness; Human-Machine Interface
ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Human Factors; Procedure
I cleared Aircraft X for take off and Aircraft Y was on short final.  Aircraft X responded we will hold short for the aircraft landing.  At that point I instructed Aircraft X to cancel takeoff clearance and hold short runway 30L. I slewed to Aircraft Y on the radar and it was showing 50kts.  The winds were 290 at 10 at the time.  I think that Aircraft Y's very slow approach speed threw of my internal clock [off] where I think he should be at compared to where he actually was.  I did check the final when I cleared Aircraft X and I didn't see Aircraft Y.  Perhaps my eye didn't pick up Aircraft Y moving because of the below average approach speed and him blending in to the sky. The radar data block for Aircraft Y had dropped prior to me clearing Aircraft X.  I think that was a small contributing factor but not an excuse.I need to more vigilant especially during high complex/traffic workloads and use my binoculars more.
A VRB Tower Controller reported clearing an aircraft for takeoff and the pilot responding that they will wait for the landing traffic. The Controller cancelled takeoff clearance and told aircraft to hold short. The Controller then went on to explain why he did not see the aircraft on short final.