SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '595865ea94a283adb7c7f58aa982d8d6021be67404f69748fc55f9b176156147' 
  AND token = 'z/JduuF5fbor3nD+z+vK0HsV2NwTAjicvZaT794SOAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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