Hey, Jo! I just have a quick question for when you have a moment: <question for Jo>
And leave it. I'll ping Jo again at a time interval depending on urgency - sometime this sprint? I'll remind about the message in a couple days. Need it today? I indicate that when I ask, and about 4hrs later I'll poke a bit to see where we are.
Expectation setting is the missing key in a lot of these conversations. Asking to ask is about not being rude. There are better ways to do this in an asynchronous conversation. It's right up there with "we need to talk" in texts. The anxiety it causes is completely unnecessary, and easily avoided with a little detail and priority.
There are countless socially defined, implicit hammers looking for nails. Most can be improved upon or swapped out for different tools.
Please just ask questions. Pinging someone about a mysterious question that you'll reveal later is annoying. It certainly doesn't go on my list of things to do re: "Sometime later this sprint be sure to get back to that person who won't tell me what they want from me". It goes on the list "Ignore this person"