It's rather difficult to look for locking wheel lugs that are a different length from oem. Additionally, different lugs need to be used if you decide to run different wheels/spacers.
Personally, I would suggest buying a stud kit, and locking lug nuts. Not only does a stud kit make wheel removal/installation much easier, you can easily throw on different spacers and re-use the same exact set of lug nuts. Many supporting vendors on this forum
have stud conversion kits for sale.
You can find locking lug nuts online as well, but remember that BMW uses lugs/studs with a 12x1.5 thread size. Personally, I bought set from Evasive Motorsports
. You can choose from open-ended or close-ended types, and there's a wide selection of colors, if you're into that.
Hope that helps!