You may avoid VBA and quick-parts by using AutoHotkey to create a shortcut macro that issues the keys that do the job.
But since you ask for an Outlook solution, here is a simple (and even somewhat tested) VBA macro to convert the currently selected text to a hyperlink of the type you requested:
Sub SelectionToHyperlink()
' Convert the current selection to a hyperlink
If ActiveInspector.EditorType = olEditorText Then
MsgBox "Can't add links to textual mail"
Exit Sub
End If
Dim doc As Object
Dim sel As Object
Set doc = ActiveInspector.WordEditor
Set sel = doc.Application.Selection
doc.Hyperlinks.Add Anchor:=sel.Range, _
Address:="https://www.google.nl/?newwindow=1&q=" & sel.Text, _
SubAddress:="", _
ScreenTip:="", _
TextToDisplay:=sel.Text
End Sub