Ok to read my script in a 3-min presentation for a conference?
If you literally read a script, word-for-word, and do not have a teleprompter, you are going to be looking down too much and not looking at your audience enough.

Even if you write a script, it would be better to have notes that help you keep the main points in order, and practice until you can give the complete talk in the required time just glancing occasionally at your notes.