The transaction have been mined by ViaBTC.

You should never use low fee if you don't want to wait a long time for confirmation, but if this happens again you can always use https://www.viabtc.com/tools/txaccelerator/ to make ViaBTC mine the tx in their next block. Just don't rely on ViaBTC or any specific pools too much because you'll still need to wait few hours for them to mine a block sometimes.