Man pages matching name curlopt_low_speed_time in section 3:

CURLOPT_LOW_SPEED_TIME.3.en	debian 10 / libcurl4-doc
CURLOPT_LOW_SPEED_TIME.3.en	debian 11 / libcurl4-doc
CURLOPT_LOW_SPEED_TIME.3.en	debian 12 / libcurl4-doc