SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fbb81e031bcaa90d70485af3363f4d9aa6288aa3b4f1bc6339a924a4541f180' 
  AND token = 'RPBYRoo3fiJ8uVwqFvPls2T8Gj081tlCNw2FYs1xbZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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