Short answer: Yes.
Long one:
Streaming is done with a pretty low speed (compared to what you would use for a VOD like a youtube video) so everyone, even with a mobile plan, can watch it.
So you can use 2000 or 2500 bitrate, which is 2 or 2,5 mbit/s, you got 63 mbit/s upload.
The maximum what is allowed on twitch.tv is 3500, other sites go higher, check their rules/ToS to see how far you can go.
And the last point is - your viewers. You have a decent connection, that doesnt apply to everyone.
So stick with 2500 on twitch until you are partnered, then you can go up to 4000.
P.S. what is more important, is your hardware. LOL is an easy game to stream and due to comic style graphics without a lot of small details, its easy to encode. But still, if you want the quality of a top streamer, you need a halfway decent PC or a top laptop.