SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '168c948b78990721031a263470da824b93d446482ec154a78cfa0084d7485210' 
  AND token = '+axkJOb3igfWVdlJZLVweyjZC8p92312rg1A3E0uiHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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