Is there a keyboard shortcut to select current line in PhpStorm?

Yes - go to Settings > Keymap and search for "Select line at caret". You can map it to any keyboard shortcut you like by right-clicking it and select "Add Keyboard Shortcut".

If you try to assign a keyboard shortcut which is already assigned to something else, PhpStorm will let you decide whether to continue or change your keybind.

Such action is available ... but assigned shortcut (if any) depends on actual keymap used.

In any case:

1. Settings/Preferences | Keymap
2. Locate Editor Actions | Select line at Caret entry (HINT: use local search box)
3. Assign any shortcut you wish (or use provided one, if that keymap has one)

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P.S. If you want to select current line to copy/cut it as a next step ... then you can just use Copy or Cut straight away -- it will copy/cut current line if no selection is made (default behaviour -- can be turned off via hidden setting).