SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e42aaa4d09d8c8212b51bfe0a026f2373e7d9d2511c26f276b3ce3f50f405c9f' 
  AND token = 'iAk0nwOgxlpEFPj9dg9TkXEz+qlPVHacv5P+4hKjBeE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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