SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c733b7ded5f7c35657aa02eedd479345effea26b63ae51f4d10e6ddd11eb2b6' 
  AND token = 'hm0BeKVLMNBLnP+cjH4BCRBgT8ifDNHv76ubWBYqiuU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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