That chance is low, but given the amount of asteroids, still bigger than winning the grand prize in a national lottery.
I think I'll quote NASA on this one.
Spoiler
The first thing to remember is that space is big and empty. Which makes the chance that we will be hit by anything from space very small. In much of space, for example, large-sized objects are hundreds or thousands of light years apart. Even the asteroid belt has so much space in it, that we can send space probes through it without any problems. The asteroids in the belt are spread over a ring that is more than a billion kilometers in circumference, more than 100 million kilometers wide, and millions of kilometers thick.
The most dangerous asteroids, capable of a global disaster, are extremely rare. The threshold size is believed to be 1/2 to 1 km. These bodies impact the Earth only once every 1,000 centuries on average. Comets in this size range are thought to impact even less frequently, perhaps once every 5,000 centuries or so.
The threshold for an impact that causes widespread global mortality and threatens civilization almost certainly lies between about 0.5 and 5 km diameter, perhaps near 2 km. Impacts of objects this large occur from one to several times per million years.
No large impact has taken place within the total span of human history... It is this juxtaposition of the small probability of occurrence balanced against the enormous consequences if it does happen that makes the impact hazard such a difficult and controversial topic.
The odds of it occurring within our lifetimes is low. There are many organizations with telescopes trained to the sky, watching and tracking asteroids and comets, compiling a list of potentially hazardous objects to keep an eye on. Many of these objects are decades away from approaching the Earth which gives us a lot of time to track them in order to accurately predict their orbits.
Actually, some 100 bodies have already been discovered on orbits which take them so close to the Earth's orbit, that they could hit in the far distant future. This is because the orbits of these bodies change slowly with time. Although their orbits do not intersect Earth's orbit at present, they could hit in a few thousand years or more.
The scenario you have in mind is most likely to unfold as follows. In the course of our search for Earth-crossing asteroids, we could find one that will hit not in the next year, or even in the next ten years, but might hit in the next hundred years. We believe that the chance that we will find such an object is only 1 in 1,000, even after a complete search.
There is a much smaller chance that we would find one that could impact in the next 10 years. The chance of that happening is 1 in 10,000.
You have a better chance of winning the lottery buddy.