SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '802a829c497f129be4874520433f456a777ee0d1867e6030141aef683baf678d' 
  AND token = 'h2AorbKtLKcWNe6uMBlj5IUNsUUqbxNZMXNYOMuDtJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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