SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c20c4395a715df4f8b4426db0d983ce114c258ac73ab6bfb6371e84246aeb948' 
  AND token = 'OrggFqkj2mBH6P/l+JU5VQgBVVweYS/MQC1ceMRlx5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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