SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56cbb8398adb26e80e8dc5b461d84a03728f47c79e8288a827cb04f0a741fc68' 
  AND token = 'wEc1JP335lsETwWDMPa3fpkFOWepSgxPazPe8dCvF4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}