SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a161ff59c72075450df66802b03fa6f901c6b494dd773b811526a88c446db072' 
  AND token = 'HhyKGsxKZvqdFhg+ICNVWApWFSVnwLrGm70d+gHSfgE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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