SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7b4552ec60fa2b02b0438d2d6e3f5b123484472797fd2296d5f18df9860cfa3' 
  AND token = 'iOZjTfBvBZsoE7zvbqGAbvrUwTnr7gZl9lMY7p6qAZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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