SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4d37e6538db789ee1f2ee8da4b80e37b9adaf5d6a9b6dd070f9ea91899905e4' 
  AND token = 'ZGYPoxwLQaYoSLMBb1CFplz/UjElmUWxd72mTr0+xwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

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