SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71403736712d0cf8a68cbf5c31d8abc3c357cd79a13d6b200b37dc6c62e7b0a2' 
  AND token = 'YVTFKOvH9rbmO8TiihS+rmxtJ5+e2LKu9DaGuONChn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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