SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '340262de9656ee459f6298a212a1ccf106490764d3ea233880a7ed29cf17eebe' 
  AND token = 'xsjKQ4P9QXT1TSiVkfY8hb3Rxnwc223ydqobLhH+ICE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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