No. A low PSA score doesn’t necessarily mean you’re ok. Likewise, a high PSA may not mean you have prostate cancer. If you’re over 45 it is VERY worthwhile getting a rectal examination. As I said, it’s not exactly pleasant, but it’s quick and could save your life.
As others have said, the PSA test isn't a reliable indicator. Get a rectal examination too. It's not necessarily pleasant, but it lasts less than a minute and it could save your life.