SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b198d4d9738fe512010546d587464d49d3b647a84b8f8c31d0d8888b93b40d9d' 
  AND token = 'ORfPIJHhsQHPmRUB4XSt8zmOUHto/5EKBd8ADXOdBJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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