SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a2ca7d1a6cad973fa6789679b368eedd08a82437998f5b42817b237bc666e94' 
  AND token = '2S3Hw0twSyQErusp5r++/A/mLxHR9+4h5RoJFOnmBmo=' 
  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"
    }
  }
}