SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c61ddc01df3e1f345986b73d2e9bcb1405069e69f5fec9b4b8b78345132c257' 
  AND token = 'zaonNvIBU9oegpHFxSI2piLwDuGCB5sNHPmiFWPypos=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}