SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79931ab924167955db826e5133d8e21c3cb6a61913c76deadbad9af039e5dd77' 
  AND token = 'o8/PpDhk9uSh4JJe5D/Or9t1gh+zQUzuxXhgX3VvXqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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