SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ade92f4281b19515f13e18268bfd5ce58aa76e99a503d58c65082c9a77a944b' 
  AND token = 'UTvwUNY9jMSs682pMgD9yCfQmpwh+tYOC8y7mBYclq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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