SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc76f04441c83cb18157f6f9f281cfeb9ddde3bbd48f20140be3e53db8fdea66' 
  AND token = 'po4QpsvSaaJkeaCM+bcZ6SXobZMxVIzYNOVwXZUBkpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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