SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'd54806a51c3f0891952d047319c0988196b43f72d7dbbf48ede36827e0a345a3' 
  AND token = 'nKxO9KrPwOXGurRXMAYikh+mfUI9P/gsYWYIQA2ZZtk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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