SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dc36fe009288fdc259639bab1b2c6deb1725caeba57abd5064007596619b45f' 
  AND token = 'MY2/hK9TGvJNoTgCWU+YCEiu1Db+0GFdjW6qrVABodw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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