Depends a little on which part of I drive you are on, but according to mapquest 50-55 minutes. Obviously how busy I 4 is through the Disney area will also affect the drive time. It's a very simple drive though.
Take I4 (25-28 miles depending on where on I drive u are) West to exit 55 ( US 27) and take US27 south for 18 miles to SR 540 , take SR 540 west for 2 miles. Total distance is about 45-50 miles mostly on 3 lane highways.
It's quite a lot closer than Busch gardens, I generally found that was at least 75-90 minutes. Map quest for I drive to Busch Gnds has it 76 miles and 85 minutes