The default shortcut keys are as follows:

Alt+↑ (Up Arrow) – Moves a line up
Alt+↓ (Down Arrow) – Moves a line down
To change the shortcut keys:

In the Visual Studio main menu go to Tools → Options
Expand Environment
Select Keyboard
In the Show commands containing box type Tools.MoveLineUp or Tools.MoveLineDown
In the Press shortcut keys box press the new shortcut keys
Click Assign