SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '503980bf0137e852e02b00367ce32540e3ea29c8de1de00e2b11a8e09cc140ab' 
  AND token = 's9LXwkY61ZUG/0KtriTPDrjzsqquL54HN9wJNN88ORs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

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