SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '476c3e6ceba9f681f54073a4f93ab38c021135d56f570d662b14635ba641cfb6' 
  AND token = 'VQpXCzX8diMX4pZVOOj/csdKFzLsYptijPuFT4qSDnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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