SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '209dcc53dc712cd36ae0d5769cd309edc4ce4ccc3220defbc359567edb50b968' 
  AND token = 'WEWvCRUEh7qHER9WZnim0EvhMyNlTy4INcGMdgpeaRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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