How do I use checkboxes in an IF-THEN statement in Excel VBA 2010?

You can try something like this....

Dim cbTime

Set cbTime = ActiveSheet.CheckBoxes.Add(100, 100, 50, 15)
With cbTime
    .Name = "cbTime"
    .Characters.Text = "Time"
End With

If ActiveSheet.CheckBoxes("cbTime").Value = 1 Then 'or just cbTime.Value
    'checked
Else
    'unchecked
End If

If Sheets("Sheet1").OLEObjects("CheckBox1").Object.Value = True Then

I believe Tim is right. You have a Form Control. For that you have to use this

If ActiveSheet.Shapes("Check Box 1").ControlFormat.Value = 1 Then