SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a52ad12eec98a89e7f68167bb48c4fa34f90424c030e69073dd28a4b5adf178' 
  AND token = 'ySfsjOQDThJbf0V+cI9dMuataNEINpfC13WdFXtymSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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