SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3aeb2c6a9463d6e07df3ad74589abd4c92c6b9668f64af34d9c395667af2b207' 
  AND token = 'GwCMqM2o++xrCp8lpj0NzOyx2P6GhHx7gwrF4Z6JMzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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