SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c18a91722d1e5328c0266b768e36b802e881acbfd93ba93764b717831cbeef35' 
  AND token = 'P1c39rFmzTkBTTGVGZPi2QQ0YtEw3yoHySaphIas17w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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