SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99ba4af83f112123420b590706154c8f13a54287febe15bd99014030c3101757' 
  AND token = 'mlUyMB7TGuvL5PeRSaI8dY/+y4X/u0wjzmAGUxUYeqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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