SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ace19b615df966047995fd44523702a30a94047e44bf4357cb1e14d8449fddc' 
  AND token = 'mQaQWK2pPZqpbqcOmxDweyCU7Xm5okCoYgprUA8g2Y4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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