Young Indian Priyanshu Rajawat also exited the season's last BWF Super 750 event.
It turned out to be a forgettable day for the Indian squad as both stars went down in straight games.
The women's doubles pair of Treesa Jolly and Gayatri Gopichand lost to top seeds Chen Qing Chen and Jia Yi Fan of China.
The most successful Indian at World Championships with five medals, Sindhu lacked any sting in her attack and went down tamely 14-21 14-21 to old nemesis Nozomi Okuhara of Japan, a 2017 gold medallist and silver winner in 2019.
Prannoy, the world number 9, who reached the quarterfinals in the last two editions, saw off the left-handed Koljonen 24-22, 21-10 to extend his head-to-head count over the Finnish player to 3-0.
The 21-year-old from Almora bounced back from an opening game reversal to keep his rival under pressure but in the end couldn't get across the fifth-seeded Christie.
Satwiksairaj Rankireddy and Chirag Shetty, who won the Korea Open, also advanced to the quarterfinals.
Lakshya, who enjoyed an 5-2 win-loss record against Feng coming into the match, had defeated the Chinese 21-18, 22-20 to win the Canada Open.
Lakshya will face second seed Li Shi Feng of China in the semifinals.
Sindhu will face China's Gao Fang Jie next, while it will be an all-Indian clash in the men's singles with third seed Sen taking on 19-year-old Sankar.