SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e55276cf1b389505aabd5eaa9de8c8dc08bc259043761cd6ca089344db922e22' 
  AND token = 'YYIPKcCKMMGhH1lGOoxzrIDVA/kuvTAq0SltODjimqU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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