SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76d36cf3a0362ec4f253b5fb8f09cdb1a6478c51cd3a5fb82c21b13fc43d32a3' 
  AND token = 'gOvRsEyDx6lMVRp6Pv9E632+uXuZ7/GjMnSiBT+qtOM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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