SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '2d50d301ba86dee951998b37a579f49907a4c4bc19a53ffb0ff91b037a337c59' 
  AND token = 'TnkKY6WzKZa2WywdHXSsufushtRZghxBFz9QhQ7e9W8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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