SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39b36846b1f0f6049f5edfb58bb23483d9a52cedeef809afc29f27326ec72de7' 
  AND token = '65ri/8L+BGk8tfsD8SfIpZ/hOOlt7q29yiwGmkUT+xU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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