SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a211d4e637ec87b91b165f0816b8677464495f986774a70aac941a264d210b52' 
  AND token = 'VyCiAk/hft3xfjyhQPF7WUaN0pyAs9PpAQhYd1bOi7Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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