The touch up paint may dry in an acceptable manner down to 30°F., but, it certainly won't flow very well there.

If your intent is to do the best possible job and minimize the "touch up" look, you want the paint to flow out and flatten itself in the depression. This is best done at warmer temperatures. If in very dire need of the touch up, I'd recommend the use of a hair dryer to keep the paint and the body warm while it dries.

Before applying the paint, you need to remove all the rust from the chip, if any, to provide a solid base for the paint to adhere. This is best done carefully with an "Exacto-knife". If the chip has been around for awhile, the rust may have grown underneath the surrounding paint. This means more work and a bigger "touch up".

You want to apply the touch up with the smallest possible brush you can find. Sometimes a toothpick is preferred. The tendency is to put too much paint on and it dries with a blob sticking up above the surrounding paint. Less paint is always preferred. You can always add more on a second application.