SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81bc76fac1941f8fc7546353f160c32dbd3e408ffe3555130b58b4ad29f56f03' 
  AND token = 'jDh3QMp6hq9KFnlVn3yJ+RdD5KltU2jnoBXcmUURIhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

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