SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b9503d8da3d58c77028e5bbc04f11047fb645f61434454274f19d7e531f4ffa' 
  AND token = '9UrfJyoGdOW1OwTgq/JjrQ/6VV18hxMQhGIv3jKFFXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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