Not that I know.

But you can start dragging and whilst keeping the mouse button down, you can hold the TAB key so you can temporarily move your selection to the exact spot you want it to. Then let go of TAB and adapt the size of your selection.

In case you know exactly where you want to start from - and you can drag from all four corners! - you can first draw guides ( view menu > rulers, or ctrl+r, then drag the guides out of the top or left side with the move tool ). Draw a horizontal and a vertical one, activate snap (view > snap, or Alt +v+n) and drag from the intersection.

In case you know the width (or height) draw your left and right (or top and bottom) guides and drag between them. Fixed ratio will give you your ratio.

To get rid of guides, drag the back into one of the sides (out of the canvas), or hide them with Ctrl+H.

Instead of Image > crop I usually prefer to use Alt+i+p

There are no Borg. All resistance is fertile.