It only takes 0.05th of a second to collect germs.
People underestimate how fast germs spread.
It's not really that the germs spread of their own accord, as in them multiplying onto your food.
The average rate of microbial reproduction is 20 minutes.
But, germs are on the floor/surfaces, and when food falls onto the germs the germs get stuck on the food.
You've probably seen cartoons joking about the 5-second rule, where one germ tells the others to charge towards dropped food, but a leader germ says "Stop, we need to wait 5 seconds".
However germs don't travel towards food, or even multiply onto it (unless the food is left for a very long time).
So it really doesn't matter how long it takes you to pick it up, as the germs get stuck to the food instantly. It simply depends on how dirty the surface is, and therefore how many germs it touches.
In perfect conditions food could sit on an antiseptic surface all day and not become bad for you.
But as Foxscoth points out, unless it's an extremely dirty surface, the germs aren't the issue.
The biggest reason not to eat food from the floor is because it will likely be covered in soil, hairs, fibres and dust, which is not nice to put in your mouth.