SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29dd5a015fd9658be5865a79cb4d21c908d76a25d183963243b7fd2f2dca2a47' 
  AND token = 'CMYpXBV6REE8JPlXVsEWGQhB9HWBR6zERAsyuHHXl44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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