SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9cc4f93baef7464d1e2c03e20440971d285026c64841173c482f3dea45da9488' 
  AND token = 'Jfl3jLpjhjuRmAZALTTQY1FOaoHxA6pXJveI5hMxJeA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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