SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15dff81c3a358dc94a52f9ec8dc84417730dd3d9ef38cd2d81371492778ad919' 
  AND token = 'EgLmvBLc/6CUvRJ8Q5VGRrHUW8hWluGKUQqFLKnZNoM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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