SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96b05d266b79bddd52210d2780b9b9d1f32a4c0cd515eebd2dfb61edbe1ed60f' 
  AND token = '9dZwgU/Aegw87qIZQ3gSJ/vgomoherZLbh/curHncTU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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