SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3b6fff72530db8a4cbebe204f80bac6835d8614e4f145fe40c2cc4e7d21d17b' 
  AND token = 'lL3CnceRl8I39DzxbbnT2jRV0mhez/CaApX/twFVDy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

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