By.CSS_SELECTOR

# 导包
from selenium import webdriver
from selenium.webdriver.common.by import By
from time import sleep
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
# 浏览器驱动
driver=webdriver.Chrome()
driver.get(r"D:\XXX\myself\1.html")
sleep(3)
# 寻找元素  点击
# 等找到元素再执行
element=WebDriverWait(driver,10)
.until(EC.visibility_of_element_located((By.CSS_SELECTOR,"#ls_username")))
element.send_keys("fqs")
# driver.find_element(By.NAME,"username").send_keys("fqs")


# 退出
sleep(2)
driver.quit()

解释

 html