SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e55bbff7b121741e72ca71798a3932587aa9eeae7be4a999b9593254009cc8b' 
  AND token = 'uxHBJrio3OQQ47vctVZB/94gaao8EfIpqL9pjKrBhMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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