"Best practices" are for academics and people who read Datamation.
You have to look at why OOP exists and then ask yourself if the function you wish to create really needs any of the values that attend OOP. You also have to look at how simple your code is to read and understand.
Based on what you've described, there would appear to be absolutely no value in making it into a class with a static method. In that case, all you would have done is to add an extra level of complexity to your code. If I were a programmer coming in after you to work with your code, I'd ask myself why in the world you did that. And if feasible, I would change it back to a flat function for the sake of simplicity.
Always prefer non-OOP unless you have some compelling reason to make something object-oriented. For example, the interface to a DBMS is something which may involve many many functions. It is definitely something which benefits from OOP code, not flat functions. I've personally found that dates benefit from this same treatment.