SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a1a6a29f97632df32ed50d3a18642ea6400bd187450d965a0165a75ac005925' 
  AND token = '3BvGo78WRe1qPdxHwxvzRPkxYee8AzYc3PyirlGcXa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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