always visible arrows in fancybox by CSS.

fancybox-css.css

#fancybox-left-ico {
  left: -45px;
}
#fancybox-right-ico {
  right: -45px;
  left: auto;
}
.fancybox-nav span {
  visibility:visible;
}

#fancybox-left:hover span {
  left: -45px;
}
#fancybox-right:hover span {
  right: -45px;
}