I managed to split the audio using ffmpeg for Windows https://ffmpeg.zeranoe.com/builds/
Unzipped the program to a desired location.
Opened cmd in Windows.
Navigated to to the ffmpeg-(version-code-here)/bin/ folder
Ran the command
ffmpeg.exe -ss 30 -i "D:\Songs\my-audio.m4a" -c copy -t 60 "D:\Songs\my-audio-splitted.m4a"
This command is splitting the audio file after -i parameter from second 30 to second 90 (30 + 60) and saving it at "D:\Songs\my-audio-splitted.m4a"
-ss 30 means the split will begin at the 30th second of the audio file
-t 60 means the split will end counting 60 seconds from the informed start, so the split will end at the 90th second
If -ss is not informed, the split will assume the start is at 0 second
If -t is not informed, the split will assume the end is the end of the audio
I am not sure what ffmpeg is doing (if its transcoding or not), but it is a really fast processing, so I am assuming it is doing what I want.
Credits for @StarGeek at the comment section.