SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2eb85c062ef2989bd66865b87adbf6550520256674dbea511141adcccd261a83' 
  AND token = '3lgBeKw6JVKzM6oujsG5pJj8k7PNfwA3nP69/gPmqBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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