John always used his clairvoyance as a crutch but when he sees himself killing an unknown woman, he must escape the crosshairs of the all-seeing organization KEN.

Using clairvoyance as a crutch is unclear - how does he actually use it to help himself, and what does this say about his character? That's what needs to come across.

Also unclear: seeing himself killing an unknown woman. One can presume he has a vision of himself committing murder, but "sees himself" is such a vague phrase that it makes one stop to think about what it means, and a logline shouldn't make anyone stop and think what it means - it should be clear. Boom, here's the story. As for the woman, to whom is she unknown? John? Everyone? KEN? Who or what is KEN anyway? Why are they after John? For not yet killing someone he doesn't know? How do they know about it? Did he tell them? Are they psychic too? What makes it okay for them to try and kill him? Why would they want to? What makes them think they could, given that he's psychic?

Some of these questions may be answered in the script itself, but raising questions with the logline never works. You want people to be intrigued by the story, and want to read the script because they're interested - not to have questions answered that they shouldn't be asking.

And in general there's no need to include names in a logline. Maybe try something like this:

"When a lazy psychic envisions himself murdering a stranger, he must find the real killer while evading another clairvoyant sent to hunt him down."

I don't know if that matches your story or not, but it gives an idea of who the protagonist is, what the conflict is, what's at stake, and the antagonist. I just said one guy because it's more specific; in a synopsis you might say the hunter works for and was sent by KEN, but putting that here, as I said, raises too many questions. Because if the organization is all-seeing, then he can't escape them, because they see all?or maybe they don't really, but again, that's too much to digest in a logline. Get someone's attention and make them want to know more, but without them asking what something means, or for an explanation.

Hopefully the revision clears some things up. I couldn't help but sound like minority report in a way. But your first guess is right. An organization of clairvoyants.

When a clairvoyant sees himself killing a woman he can't see, he must escape the crosshairs of the all-seeing organization KEN, whose kidnapping others just like him.

Not sure about how many words should be in the logline, one person said 27, another 30, another 25. So I aimed for 27 which made this insanely hard because the woman being unknown isn't the bite. But I swapped out "he can't see" for "unknown" to save space. I was wondering if i should also swap clairvoyant for psychic but that was me just trying to sound different.