SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf204a15085b59f597d3ab23ff6ee7d6ffe36e828bbf472dc02e5d238b8a4306' 
  AND token = 'UIElpjkOgbjUsmz3dgkxx9B9xmcrvJzy6zFL2wKqVXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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