SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '163f52c7a587f96f4e0c385b6978b21e5f791199be1e46b2b8a936ce441ef2a9' 
  AND token = '6j1BJMC4znxXuDgEgHtkfwMB1YtDshqCquywfrZtJe0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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