SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '956b3eff7adb4e39cec970201707b30e68b05344d6c0a3f1c7752acce2de1b8c' 
  AND token = 'k3wfkhoLw7wqG/7XsF+lrEq7YnV6Sh/EjVIdzeWPRQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE Impossible WHERE noticed after reading const tables