simplify check

mixing/mixpool/mixpool.go

@@ -1397,7 +1397,7 @@ func (p *Pool) checkAcceptKE(ke *wire.MsgMixKeyExchange) error {
 
 	now := time.Now()
 	keEpoch := time.Unix(int64(ke.Epoch), 0)
-	if now.Before(keEpoch) && keEpoch.Sub(now) > earlyKEDuration {
+	if now.Add(earlyKEDuration).Before(keEpoch) {
 		err := fmt.Errorf("KE received too early for stated epoch")
 		return ruleError(err)
 	}