SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e832993234b4527d53141aedf1361d2e64dc69434ec8abd5e6d7fb45bce2ff2' 
  AND token = 'LhNJuyRSMaS8dUOYMICFn2kkGC0U9GdPFVjNjnoCdcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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