Wait, I missed this.
CREATE UNIQUE INDEX IX_IX ON Table (Col1, Col2)
You're only skipping rows 1-8 where col1 = 10
Unless you go up to thousands of values in Col2, it really doesn't make much difference in time between a seek and a scan. But I just tested your original query against my UNION ALL suggestion, and your original query actually produces the most efficient query plan. Just a straightforward index SEEK, instead of the index scan I feared. Go for it.
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Against stupidity the gods themselves contend in vain. -- Friedrich Schiller
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