Can't even have an inkling of a friendship with a woman without thinking of sex

I will preface this by saying that I'm a single guy. It seems like anytime I'm on the verge of forming a friendship with even a slightly attractive woman, there's part of my mind that immediately considers if it would be possible to have sex with her.

As one example, I sit in one of the local coffee shops a few times each week with my laptop doing some work. There's often another woman there (in her 50s) working on her laptop, and we've gotten in the habit of chatting for a bit about books we've read, etc. My problem is that I can't just accept a platonic friendship (even a relatively shallow one) without thinking of other things. Any sort of friendship that I establish with a woman (in any situation) starts me thinking of blowjobs, sex, etc.

I have no doubt that most men operate like this, but for me it's becoming excessive.