SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2858c97f30017a4533be5886f32296a6381b6a52564cf5727c6e834be9be53a3' 
  AND token = 'PrjaEaFXR37qJIOFKCKofuNn95v49amnNaTAnz/iv/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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