SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3944d82b60ac498ee86b50939879917291530defd64424aa50687d386b776d7a' 
  AND token = '9pO9aUc2zNsTSAC8pvXz3ufBjjYBCDyq0Io4HTdOS1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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