SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3355b1817ba82f654bfb8ac5637ada4abbbc5d7a83947bfeeecc292612e5c50' 
  AND token = 'm/ERuh2t/OFfHmrPSlpfjCTSn6v2jYQ/w4Y+lKo+PnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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