<tr>
    <td class="column-text">column 1</td>
    <td class="column-text">column 2</td>
    <td class="column-text">column 3</td>
    <td class="column-text">column 4</td>
    <td>last column has not class</td>
</tr>

tr td.column-text:last-child {
    color: red;
}