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

a.cp_btn {
  position: relative;
  display: block;
  width: 160px;
  padding: 0.8em;
  text-align: center;
  border: 3px solid #9C27B0;
  text-decoration: none;
  transition: all .4s ease-in-out;
}
a.cp_btn::before,
a.cp_btn::after {
  position: absolute;
  top: -3px;
  right: -3px;
  bottom: -3px;
  left: -3px;
  content: '';
  z-index: 2;
  transition: all .4s ease-in-out;
}
a.cp_btn::before {
  border-top: 3px solid #FF5722;
  border-bottom: 3px solid #FF5722;
  transform: scale(0, 1);
}
a.cp_btn::after {
  border-right: 3px solid #FF5722;
  border-left: 3px solid #FF5722;
  transform: scale(1, 0);
}
a.cp_btn:hover {
  color: #FF5722;
}
a.cp_btn:hover::after,
a.cp_btn:hover::before {
  transform: scale(1);
}