SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42c0787a91778a7d896be9328b1faa17d2b67a5c5808ca316dde76f47f2840ea' 
  AND token = '5TgvBYWKU+uUgrtG66nfXIj1IQunTfY/IRb+wR/alcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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