SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03d255eedd8f10fb0e3dd60542309a77ec65cd296d0e59f4f73e8c500859e1a3' 
  AND token = 'gPlrACHGGuG8JMQiYqNE3wDGV41XffmUxFCZcRC5E70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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