SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b74c00f81973dc32fb9ea0973fc2298cb8ed02d2de4e91af55d3569339bd8fa' 
  AND token = 'pZk9eu0QxblP5dKPOxiCh+Ngn7iWbYMKbzqKj5/GXB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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