Finding useless unit tests with PIT

Assume we have a code we'd like to test:

class C {
    int doSmth() {
        return 1;
    }
}

Now assume we have 2 unit tests placed within a single class. The 1st one "test everything" while the 2nd one "does nothing":

@RunWith(JUnit4.class)
public final class CTest {

    @Test
    @SuppressWarnings("static-method")
    public void testDoSmth() {
        assertEquals(1, new C().doSmth());
    }

    @Test
    @SuppressWarnings("static-method")
    public void testDoSmth2() throws Exception {
        Thread.sleep(1000);
    }
}

This is an IRL example: I've seen dozens of tests "fixed" by replacing the test contents with some useless code, as the contract of code being tested changes over time.

Now, PIT "entry" unit is a class containing test methods (not an individual test metod itself), so in the above case PIT will not only show 100% line coverage, but also 100% mutation coverage.

Okay, I'm relieved to know I have 100% mutation coverage, but how do I identify a useless test -- testDoSmth2() in the above case (provided my mutation coverage is high)?