@benzil, I switched to a computer where Groove is my default mp3 player, and it worked for me to use the quoted full path to he mp3 file, but then I googled and found this page that suggested this command line:
cmd /c start "explorer.exe shell:C:\Program Files\WindowsApps\Microsoft.ZuneMusic_3.6.25021.0_x64__8wekyb3d8bbwe!Microsoft.ZuneMusic" "C:\Users\Russ\Music\03 - Take a Chance on Me.mp3"