code: func (h *Helper) GetMvccByEncodedKey(encodedKey kv.Key) (*kvrpcpb.MvccGetByKeyResponse, error) {
  	keyLocation, err := h.RegionCache.LocateKey(tikv.NewBackoffer(context.Background(), 500), encodedKey)
  	if err != nil {
  		return nil, errors.Trace(err)
  	}
  
  	tikvReq := &tikvrpc.Request{
  		Type: tikvrpc.CmdMvccGetByKey,
  		MvccGetByKey: &kvrpcpb.MvccGetByKeyRequest{
  			Key: encodedKey,
  		},
  	}
  	kvResp, err := h.Store.SendReq(tikv.NewBackoffer(context.Background(), 500), tikvReq, keyLocation.Region, time.Minute)
  	if err != nil {
  		logutil.Logger(context.Background()).Info("get MVCC by encoded key failed",
  			zap.Binary("encodeKey", encodedKey),
  			zap.Reflect("region", keyLocation.Region),
  			zap.Binary("startKey", keyLocation.StartKey),
  			zap.Binary("endKey", keyLocation.EndKey),
  			zap.Reflect("kvResp", kvResp),
  			zap.Error(err))
  		return nil, errors.Trace(err)
  	}
  	return kvResp.MvccGetByKey, nil
  }
docs: // GetMvccByEncodedKey get the MVCC value by the specific encoded key.