SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a5ec4b46a2b7df9c7b86d913f57b0fc8c3b5f832a712aa15bd21843285535dd' 
  AND token = 'Sp5lb7Y1IYzvVHGsmYvDmxutJI9Jc9cCrSXB85XIXBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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