SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '239ad935a8d444634eef3f6e1b1c1156de89a6b0e3305558c3a068c5875573cd' 
  AND token = 'osYAfaTAkwa2EQWCWVQLuRBGHqYQL7IEH7hsqBgATXU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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