Is it safe to eat a non-refrigerated store-bought pizza base?
The default answer is NO. You don't know how long the pizza bases have been left outside, but most likely more than 4 hours.

Before you open the package, see if it's vacuum packed or in a protective environment. If it's vacuum packed but bulging, throw it out, it can have dangerous levels of botulism toxins that are mortal. If it's not vacuum packed and bulging, you don't know...

You should open the package and smell. Yeast doesn't smell pleasant, but it has a distinctive smell. So, if it smells like yeast, and if you don't see any dark spots (of mold) on the base, and if you are a healthy adult, you could risk it (at your own risk). If you do see mold, just throw it out.

Do not give risky food to children or the elderly, ever. 

At any rate, for the price of a pizza base, just throw it out. Make your own pizza base! Even cheaper than store bought and more fun.