Actually, in this case it's quite simple: apply the vertical align to the image. Since it's all in one line, it's really the image you want aligned, not the text.

<!-- moved "vertical-align:middle" style from span to img -->
<div>
  <img style="vertical-align:middle" src="https://placehold.it/60x60">
  <span style="">Works.</span>
</div>

Tested in FF3.

Now you can use flexbox for this type of layout.

.box {
   display: flex;
   align-items:center;
}

<div class="box">
    <img src="https://placehold.it/60x60">
    <span style="">Works.</span>
</div>