Yes, you can ask, but you will almost certainly be turned down for such a request, because journals do not normally keep separate templates for single-column layouts. Moreover, at the type used by journals, a two-column format is essential because long lines of text are difficult to process. (Readability studies show that about 65 to 70 characters per line works best.)
That said, many journals do have to deal with long equations, and in such cases they will have equations that cut across both columns, and indicate how the text "flows" around the equation. As Jon Custer's comments indicate, if there are enough such equations in a row, the page in question may be set in a single-column format, before reverting back to two-column format after the "run" of equations is broken up.
As an example of how this looks, here's a page from a paper published in Physical Review D: