SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03a9c1d616d7b187cd9d07d7508bf9dcdad1c028d7befad5aa95001590263c18' 
  AND token = 'QqEDz4N6tQ33XVgJPOR5EKCxhG2fv3uWyYWIU5Uvx54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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