Can Muslims (including men) have braided/locked hair?

yes.  both male and female. 

There was a female companion at the time of the prophet s.a.a.s. who said she finds it hard to do ghusl (ritualistic bathing) because her hair is in locks / braided.  She was told it is sufficient for her if she uses her fingers to wet the roots of her hair. (Remember islam makes life easy, not difficult - the prophet s.a.a.s. said: "Religion is very easy and whoever overburdens himself in his religion will not be able to continue in that way. So you should not be extremists...[Sahih Bukhari, Volume 1, Book 2, Number 38]"

Sahih Muslim Hadith 643 Narrated by Umm Salamah
I said: O Messenger of God (saas), I am a woman who has closely plaited hair on my head; should I undo it for taking a bath, because of sexual intercourse? He (the Prophet (saws)) said: No, it is enough for you to throw three handfuls of water on your head and then pour water over yourself, and you shall be purified.

Sunan of Abu-Dawood Hadith 359 (part) Narrated byUmm Salamah
.. As regards the (ghusl of the) woman who had plaited hair - sometimes each of us had plaited hair - when she washed, she would not undo the hair. She would instead pour three handfuls of water upon her head. When she felt moisture in the roots of her hair, she would rub them. Then she would pour water upon her whole body.


Sunan of Abu-Dawood Hadith 255 Narrated by Thawban
Shurayh ibn Ubayd said: Jubayr ibn Nufayr gave me a verdict about the bath because of sexual defilement that Thawban reported to them that they asked the Prophet (saws) about it. He (the Prophet (saws)) replied: As regards man, he should undo the hair of his head and wash it until the water should reach the roots of the hair. But there is no harm if the woman does not undo it (her hair) and pour three handfuls of water over her head

As for men - the prophet yahya a.s. (John the Baptist) was reported to have had dreadlocks.  So if a prophet can have it - who can say we can not?  following the examples of previous prophets of islam is recommended (unless it contradicts God's laws or the Prophet's Sunnah) - otherwise their examples would not be given in the quran. Braiding mens hair does not contradict the quran nor sunnah. In fact, the propet muhammad s.a.a.s. practised this on at least one occasion

"The Prophet s.a.a.s. traveled to Makkah and he had his hair in four braids." 
- Aboo Daawood (#4185), Ibn Maajah (#3631 according to Al-Albaanee), and Al-Albaanee authenticates it in Ash-Shamaa'il Al-Muhammadiyyah (#23)