Sub www()
Dim i&, y&
For i = 1 To Cells(Rows.Count, 1).End(xlUp).Row
          For y = 1 To 17
              If (Asc(Mid(Cells(i, 1), y, 1)) >= 48 And Asc(Mid(Cells(i, 1), y, 1)) <= 58) Or _
                  (Asc(Mid(Cells(i, 1), y, 1)) >= 65 And Asc(Mid(Cells(i, 1), y, 1)) <= 70) Or _
                  (Asc(Mid(Cells(i, 1), y, 1)) >= 97 And Asc(Mid(Cells(i, 1), y, 1)) <= 102) Then
                  Cells(i, 2) = True
              Else: Cells(i, 2) = False: Exit For
              End If
          Next
Next
End Sub

Sub qwerty()
Dim i&, y&, x(), rez()
x = Range("A1:A" & Cells(Rows.Count, 1).End(xlUp).Row).Value
ReDim rez(1 To UBound(x), 1 To 1)
With CreateObject("Scripting.Dictionary")
        .CompareMode = 1
For i = 1 To UBound(x)
        For y = 1 To 17
            If (Asc(Mid(x(i, 1), y, 1)) >= 48 And Asc(Mid(x(i, 1), y, 1)) <= 58) Or _
                (Asc(Mid(x(i, 1), y, 1)) >= 65 And Asc(Mid(x(i, 1), y, 1)) <= 70) Or _
                (Asc(Mid(x(i, 1), y, 1)) >= 97 And Asc(Mid(x(i, 1), y, 1)) <= 102) Then
                rez(i, 1) = True
            Else: rez(i, 1) = False: Exit For
            End If
        Next
Next
End With
[B1].Resize(i - 1) = rez()
End Sub