SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73a8e69d9e904a31b25ba483dcad329b78cd4fc20b79a1042138c4b5ad0c589e' 
  AND token = 'q7uBdNbF4VuWreTgyb7JZfvjcOmlHrUVQLd2zHLG5Nc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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