One. Saying “hey” changes their view of you. It’s very possible that opening with “hey” will actually shift their opinion of you towards negative. To me (and friends I’ve talked to) it comes off as very low effort, which is unappealed.
Two. You’re going to need to write a better message anyway. Some people might have success with the “hey” “hey” “how’re you?” “Good u?” flow but I really strongly recommend not doing that. It takes longer, a lot of people dislike it, and you’re going to eventually have to write something better anyway. Opening with a good message saves you time overall.
Sending a good initial message saves you time overall and increases your success rate.