The word Kyrios is very rarely used in this way and almost exclusively in prayers.
In the common use it means mister
In Biblical Greek it’s very common!
It's really not as soft as "Mister" either. It does ascribe authority and honor to someone, but since our culture is largely devoid of this kind of honoring, it's difficult to translate. In honor/shame cultures it would be a much more common concept used of fathers, mothers, husbands, bosses, political leaders, elders, etc.
The closest we have is the way we refer to judges, "Your honor." Another way to think of it is the way the title "Doctor" gives honor to someone, but this word doesn't have any idea of education with it. It's similar to the old English way of saying, "My Lord."
You could also say, "master," the way the Ninja turtles referred to Splinter (without the concept of slavery).
There is also an interesting etymological connection between the Greek word "kurios" and the Hebrew word "Yahweh," which is one of the reasons Jesus is called Lord often in the Bible.