SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd55ac169fc3545bb73b8e39c08b2f4cdfc36fe92d6ff45cf95b11b2a1680b2c6' 
  AND token = 'MCBc7nPnWAhMJ3pNCqQuozF8PvfjvrIK83oLCDG0KAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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