SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '504ed59639d44fe1fd49f6475d56f3886a7e41e4030f0195569c7d0d6906d6b6' 
  AND token = 'mcJZYE2qRrZ9F4fHiPZpzTqBw89RpN1+CwWCubJPVno=' 
  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"
    }
  }
}