SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36d6cb9bf6079f8c1ffca38b46087ff41fcae01e56c87d28917018408dec7464' 
  AND token = 'dd5sBZ57ADTXdfzCx+06yhri45SEzMLZRV46AmrDAyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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