SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0450dfd785f22b8b245221e49fd1e66e3647775bcdf043a49523f07eb8f5227b' 
  AND token = 'a6AF0GmG3EMArhA2QIfmBCZKnAZkSXjpxbD14vo6WZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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