SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '851fc957076234ee37817ce6e5f6308831d0cb7e13dd02848a72f152851db955' 
  AND token = 'JLaltWa2njJORqgnf3eEAXT/DXK7pWHB3x7JNFGQNOw=' 
  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