SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b7b53faec8d24d78c331d162ac10a1521f0cdad0990d1516c0646e56c3d6c59' 
  AND token = 'gjxepFvgsP5leS0YZcTF9PgPVnYLqbqwPOzHFIbCsGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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