No, you can't.
The Kolmogorov-Smirnov test is used to test whether two distributions are equal. What you are interested in is whether two distributions have the same mean.
For instance, two distributions $(1,2,3)$ and $(2,2,2)$ are unequal, and the KS test would detect this (except for the sample size, which is too small), but their means are equal, so the KS test is misleading for you.
What you want is a t test, which tests equality of means. It comes in various flavors. You want the "unpaired" one, because your data are unpaired, and you should take a look at your data to decide whether you can assume equal variances in your two populations.
Note, however, that you have a very large sample. Any test will return a statistically (!) significant difference in means even if the difference is tiny, simply because the sample size is so large.