SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce5e08ed8362a00de449eb50efd4ec0598420af5259c08685a070edf5cfa0c7f' 
  AND token = 'LffA31x5UiXMWudeweATwnLOcoSUrp4Nrat4maqeswg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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