SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9724c63421d5b64059f9a1ecad7015c4b594e9faaaec1c3c751aaeb645cf7e6' 
  AND token = 'gtGKCN6cyzP5PWWzhAEVOsj5//QisJ2GZ6CLsp91JeY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

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