SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e3eef3cfa6836efca96824371e4564b94242cc769b74b2de6307dc51842ff45' 
  AND token = '/8u/3l9PxmDV/0kuFs1bZEThuTgKRxHqWXjHkJ8Djys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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