Your first column in the index is cl_totalcrawltimes.
In the WHERE clause you're using this column to define a lower range (cl_totalcrawltimes > 0).

Depending on the data distribution this most probably will lead to an index scan instead of an index seek.
Furthermore, cl_crawlsource is not part of the index (the include section, preferrably), so this would require a clustered index key lookup anyway.

Therefore, SQL Server ignores the index since it seems to be more efficient to perform a clustered index scan.

For best results, make those columns on which you query for an exact match the first columns of your nonclustered index. (Whether the next column should be your inequality column or your order by column depends on what the optimizer likes, if any.)