<a href="#" class="cp_btn">button</a>

a.cp_btn {
  position: relative;
  display: inline-block;
  width: 160px;
  padding: 0.8em;
  text-align: center;
  text-decoration: none;
  font-weight: bold;
  color: #FBC02D;
  border-top: 2px solid #FBC02D;
  border-bottom: 2px solid #FBC02D;
}
a.cp_btn:before,
a.cp_btn:after {
  position: absolute;
  top: -7px;
  width: 2px;
  content: '';
  height: calc(100% + 14px);
  background-color: #FBC02D;
  transition: .3s ease-in-out;
}
a.cp_btn:before {
  left: 7px;
}
a.cp_btn:after {
  right: 7px;
}
a.cp_btn:hover:before,
a.cp_btn:hover:after {
  top: 0;
  height: 100%;
}
a.cp_btn:hover:before{
  left:0;
}
a.cp_btn:hover:after{
  right: 0;
}