SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21d143769524e1ef2654b1ad64f96923b38a30874163e0cb43485471ab65c498' 
  AND token = 'DpbCzk2WP3I/J9GFJgxJSqmNwoi6hTUJVA/d5LH6D6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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